Synthesis and characterization of ordered mesoporous SiO_xN_y thin films with different nitrogen contents

摘要

Work on the synthesis and characterization of well-ordered mesostructured SiO_xN_y thin films (MSONTFs) on silicon wafers is described in this paper. The MSONTFs, characterized by high surface area, good order and uniform mesopores, were prepared by thermally treating the calcined mesoporous silica thin films (MSTFs) on silicon wafers in flowing ammonia at high temperatures. The nitrogen content of the MSONTFs was controlled by simply changing the nitridation temperature. At the same time, the specific surface area and wall thickness of the MSTFs all decreased with increasing nitridation temperature. X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FT-IR) spectroscopy confirmed that nitrogen was incorporated into the framework of the MSTFs. High-resolution transmission electron microscopy (HRTEM), small-angle x-ray diffraction (XRD) and N_2 sorption evidenced good structural ordering of the MSONTFs obtained. Scanning electron microscopy (SEM) images of cross sections and the surfaces of the samples showed that the MSONTFs on the Si substrates were continuous, homogeneous and did not crack, though there was evident shrinkage after the MSTFs were thermally treated in flowing ammonia at high temperatures.